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Kawasaki Ki 48 Lily

Captured Ki-48 in China after the war.

The Kawasaki Ki-48 was a nicely
designed aircraft, fast, manoeuvrable, and well armed both offensively
and defensively-for its time, which was the late 1930s and up
through early 1942. Then, the changing pattern of the air war over the
Pacific-Asian battlefronts, and the changing operational requirements,
left this trim little twin-engined light bomber behind. Although its
production ended in October 1944 with 1,977 examples built, it
remained in service because, by that date, Japan was plainly losing
the war, and was in dire need of virtually anything that could
fly-particularly for "special" (suicide) attacks.

Early in the Sino-Japanese War of
1937, China deployed numbers of Russian-built Tupolev SB-2 light
bombers, sometimes crewed by Soviets, on hit-and-run attacks against
the Japanese invaders. The Japanese were surprised by this aircraft's
speed; it was faster than the Ki-10 biplane fighter, and was nearly as
fast as the Ki-27 monoplane fighter which was just entering service
with the Japanese Army Air Force. Certain air staff officers were so
impressed by the SB-2's performance that they obtained the go-ahead to
begin development of a similar light bomber for the JAAF. Kawasaki
Aircraft Ltd. was issued the specifications in December 1937. These
called for a twin-engined light bomber with (a) a top speed of 298 mph
at 9,845 feet; (b) a cruising speed at the same altitude of 217 mph;
(c) climb to 16,405 feet in 10 minutes; (d) a bombload of 882 pounds;
(e) engines to be Nakajima Ha-25 radials; (f) defensive armament of
three or four flexible 7.7mm machine guns; and (g) ability to operate
under the extreme winter conditions prevailing in Manchuria and North
China.

Actual design work began in January
1938 with Dr. Takeo Doi in charge, but because he was also in charge
of the Ki-45 twin-engined fighter design team, and the Ki-45 had a
higher priority, the first prototype of the new light bomber wasn't
ready for flight until more than a year and a half passed, in July
1939. Experience gained from designing the Ki-45 was incorporated into
the bomber project. The cantilever wing was mid-mounted to allow an
internal bomb bay. The crew of four was to consist of the pilot, a
bombardier/nose gunner with a 7.7mm weapon at his disposal, a
radio-operator/gunner manning the dorsal 7.7mm machine gun, and a
navigator/gunner utilizing the ventral 7.7mm gun. Normal bombload was
to be twenty-four 33-lb. bombs or six 110-lb. bombs, and the twin
engines were, as per the requirements, Nakajima Ha-25s driving
three-bladed variable-pitch propellers.

Ki-48 parked at a forward airfield in either China or the Philippines,
1944.

During the prototype's flight trials,
it easily met all performance requirements and won praise from Army
test pilots for its manoeuvrability and handling characteristics, but
it suffered from severe tail flutter. Five further prototypes, built
between September and November of 1939, tested various tail-surface
modifications, until it was found that raising the horizontal
stabilizers approximately 13 ¾ inches and generally strengthening the
rear fuselage was the combined solution to the flutter problem. Very
late in 1939, quantity production of the new light bomber commenced
under the designation Army Type 99 Twin-Engined Light Bomber Model
1A, or Ki-48-Ia.

The first production Ki-48-Ia was
completed in July of the next year, and by that autumn, the 45th
Sentai (Group) was re-equipped with the new aircraft and deployed
to the North China battlefront, where the Ki-48 swiftly won a high
reputation with its crews. Facing largely token Chinese opposition,
the Ki-48 performed satisfactorily, winning much praise for its high
speed. In addition to daylight tactical sorties, night strategic
attacks were pioneered by the 45th Sentai, in preparation for
similar attacks on the forces of the Western Allies in the upcoming
Pacific War. Late production Ki-48-Is were designated Ki-48-Ib,
differing from the earlier model solely in having minor internal
equipment changes and improved machine gun mountings.

When the Pacific War began, the Ki-48
was the most important JAAF light bomber outside the Chinese front;
the older single-engined Ki-30 and Ki-32 were retained for China
service. Aircraft of the 8th, 27th, 75th, and 90th Sentais were
deployed against Commonwealth forces in Malaya and Burma, and against
the Americans in the Philippines, before being transferred to the
Dutch East Indies, and later to New Guinea. But against Allied
fighters of more modern vintage, the Ki-48-I fared badly; the high
turn of speed it was so praised for over China was too low to allow
the Lily, as the Allies code-named it, to avoid interceptors. Also,
its defensive armament was wholly inadequate, its bomb load was too
small, and it lacked any form of crew or fuel-tank protection. To
limit combat losses, the early model Lilies were used for night
attacks whenever possible, reducing their effectiveness even more.

Close-up of the Ki-48's ventral gun position.

An improved model of the Lily
was already being developed as the Pacific War commenced. The
Ki-48-II differed little from its predecessor, but it incorporated
a slightly lengthened fuselage, improved engines (Nakajima Ha-115s
with a two-stage blower), some fuel-tank protection, and some armour
for the crew, including a 12.5mm plate behind the bombardier's seat, a
6.5mm plate under the pilot's seat, 16.5mm armour behind the pilot's
seat, and 16.5mm plates to protect the dorsal and ventral ammunition
boxes. Within two months of its first flight, the Ki-48-II entered
production as the Ki-48-IIa. These production planes differed
from the prototypes only in minor details, such as local strengthening
of the fuselage. The Ki-48-IIb was a dive bomber, fitted with
retractable dive brakes under the outer wings (these were of the
"snow-fence" variety).

The maximum bomb-load of the Ki-48-II
was double that of the -I, but it was still a great deal less than
that of the standard Allied light bomber, the A-20 Havoc. And although
the speed of the Ki-48-II was superior to that of the -I, it was still
not fast enough to outrun the improved Allied fighters of the
later-war period. But its worst failing was its woefully inadequate
defensive armament, which had not been improved since the prototype
first flew. The Lily proved to be "easy meat" in the air, and
large numbers were also destroyed on the ground in New Guinea despite
Japanese efforts to disperse and camouflage the planes on their jungle
airstrips.

An attempt to fit a single example of
the Lily with a 20mm cannon in a revolving turret was
unsuccessful due to the increased weight and the complication of such
a fitting on a plane as small as the Ki-48. The final production
variant, the Ki-48-IIc, received a 12.7mm machine gun in a
flexible dorsal mounting, plus a second nose-mounted 7.7mm machine
gun; the bombardier could use either gun as needed. Still, despite all
attempts to keep the Ki-48 a viable warplane, it was obvious the type
was obsolescent, and so production ended in the autumn of 1944, as
noted above. Some Ki-48-IIs continued to serve in a conventional
bombing role, mainly at night, in the Philippine and Okinawan
campaigns. But most surviving Lilies were expended in daylight
suicide attacks in the latter campaign, usually en masse, in
the Kikusui (Floating Chrysanthemum) raids. A number of
Ki-48-IIs were modified as Ki-48-II-KAI special attack planes
by the Army Air Arsenal at Tachikawa. These carried a 1,764-lb.
bombload, triggered upon contact with the target by means of a long
rod protruding from the aircraft's nose like a mosquito's proboscis.

Ki-48 abandoned in the Philippines, 1945.

Four Ki-48-IIbs were used in 1944 to
test the Kawasaki I-Go-I-B air-to-surface guided missile, and another
Ki-48-II was used to test the experimental Ne-O turbojet in flight; to
accomplish this, the bomb-bay doors were removed and the jet engine
was slung under the fuselage. In addition, two proposed but
never-built variants were the Ki-81 formation commander's aircraft,
heavily armed and armoured; and a single-seat special attack aircraft,
the Ki-174.